For riscv64/rva22u64 and above, we can intrinsify math/bits.OnesCount
using the CPOP/CPOPW machine instructions. Since the native Go
implementation of OnesCount is relatively expensive, it is also
worth emitting a check for Zbb support when compiled for rva20u64.
On a Banana Pi F3, with GORISCV64=rva22u64:
│ oc.1 │ oc.2 │
│ sec/op │ sec/op vs base │
OnesCount-8 16.930n ± 0% 4.389n ± 0% -74.08% (p=0.000 n=10)
OnesCount8-8 5.642n ± 0% 5.016n ± 0% -11.10% (p=0.000 n=10)
OnesCount16-8 9.404n ± 0% 5.015n ± 0% -46.67% (p=0.000 n=10)
OnesCount32-8 13.165n ± 0% 4.388n ± 0% -66.67% (p=0.000 n=10)
OnesCount64-8 16.300n ± 0% 4.388n ± 0% -73.08% (p=0.000 n=10)
geomean 11.40n 4.629n -59.40%
On a Banana Pi F3, compiled with GORISCV64=rva20u64 and with Zbb
detection enabled:
│ oc.3 │ oc.4 │
│ sec/op │ sec/op vs base │
OnesCount-8 16.930n ± 0% 5.643n ± 0% -66.67% (p=0.000 n=10)
OnesCount8-8 5.642n ± 0% 5.642n ± 0% ~ (p=0.447 n=10)
OnesCount16-8 10.030n ± 0% 6.896n ± 0% -31.25% (p=0.000 n=10)
OnesCount32-8 13.170n ± 0% 5.642n ± 0% -57.16% (p=0.000 n=10)
OnesCount64-8 16.300n ± 0% 5.642n ± 0% -65.39% (p=0.000 n=10)
geomean 11.55n 5.873n -49.16%
On a Banana Pi F3, compiled with GORISCV64=rva20u64 but with Zbb
detection disabled:
│ oc.3 │ oc.5 │
│ sec/op │ sec/op vs base │
OnesCount-8 16.93n ± 0% 29.47n ± 0% +74.07% (p=0.000 n=10)
OnesCount8-8 5.642n ± 0% 5.643n ± 0% ~ (p=0.191 n=10)
OnesCount16-8 10.03n ± 0% 15.05n ± 0% +50.05% (p=0.000 n=10)
OnesCount32-8 13.17n ± 0% 18.18n ± 0% +38.04% (p=0.000 n=10)
OnesCount64-8 16.30n ± 0% 21.94n ± 0% +34.60% (p=0.000 n=10)
geomean 11.55n 15.84n +37.16%
For hardware without Zbb, this adds ~5ns overhead, while for hardware
with Zbb we achieve a performance gain up of up to 11ns. It is worth
noting that OnesCount8 is cheap enough that it is preferable to stick
with the generic version in this case.
Change-Id: Id657e40e0dd1b1ab8cc0fe0f8a68df4c9f2d7da5
Reviewed-on: https://go-review.googlesource.com/c/go/+/660856
Reviewed-by: Carlos Amedee <carlos@golang.org>
Reviewed-by: Meng Zhuo <mengzhuo1203@gmail.com>
Reviewed-by: Mark Ryan <markdryan@rivosinc.com>
Reviewed-by: Dmitri Shuralyov <dmitshur@google.com>
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
The test directory contains tests of the Go tool chain and runtime.
It includes black box tests, regression tests, and error output tests.
They are run as part of all.bash.
To run just these tests, execute:
../bin/go test cmd/internal/testdir
To run just tests from specified files in this directory, execute:
../bin/go test cmd/internal/testdir -run='Test/(file1.go|file2.go|...)'
Standard library tests should be written as regular Go tests in the appropriate package.
The tool chain and runtime also have regular Go tests in their packages.
The main reasons to add a new test to this directory are:
it is most naturally expressed using the test runner; or
it is also applicable to gccgo and other Go tool chains.
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